The invention relates to a carabiner comprising                a fixed C-shaped body having a first end provided with a securing part,        a gate movable around a spindle between a closed position and an open position, said spindle being situated close to the second end of the body,        a first return spring biasing the gate to the closed position by engagement of the securing part in a latching part of the gate,        and a blocking device comprising a movable locking part biased by flexible means to a locked position for automatic locking of the gate in the closed position.        